Series Of Tests Research Articles

Historical origins of corruption in the Romanian public health system - path dependency and contagion effect

BackgroundIn this paper, we estimate the long-lasting influence of the former Habsburg Empire's border on the territory of Romania, specifically on the prevalence of corrupt behaviour and practices in health services.MethodsEmploying microdata from the 2016 Life in Transition Survey and applying ordered probit regression, we explore the hypothesis that the geographical proximity of respondents' residences to the former imperial border—restricting the analysis within a bandwidth of 50 km, 75 km or even 100 km on either side – significantly influences current individual tendencies towards corrupt behaviour.ResultsThe results indicate that individuals in Transylvania living in the immediate vicinity of the former border of the Habsburg Empire (no more than 75 km away) show a higher propensity towards corrupt behaviours, similar to those from Moldova and Wallachia who reside in the same bandwidth but to the east of the former historical border. Interestingly, on one hand, after a series of tests with various relevant factors, the contagion effect is observed from right to left, meaning from those in Moldova and Wallachia towards those in Transylvania, and not the other way around as might be expected based on other previous studies. On the other hand, individuals living more than 75 kms west of the former historical border show clear reluctance to engage in informal payments and gift-giving when interacting with the public health system as patients.ConclusionBy rigorously controlling for various variables that comprehensively show different legacies of the communist regime, our results confirm the persistence of these influences across different bandwidths, thereby corroborating the hypothesis of path dependence influenced by the former Habsburg Empire.

Characterization, impact and wear properties of treated and as-received graphene nanosheets reinforcement in epoxy resin composites

PurposeThis study aims to explore the enhancement of mechanical properties in epoxy resin composites through the incorporation of graphene nanoparticles, focusing on their impact and wear resistance. It investigates the role of graphene, both treated and untreated, as a reinforcing agent in composites, highlighting the significance of nanoparticle dispersion and surfactant treatment in optimizing mechanical performance.Design/methodology/approachEmploying a novel dispersion technique using a drawing brush, this research contrasts with traditional methods by examining the effects of graphene nanoparticle concentrations treated with surfactants – Polyvinylpyrrolidone (PVP) and Sulphonated Naphthalene Formaldehyde (SNF) – on the mechanical properties of epoxy resin composites. The methodology includes conducting a series of impact and wear tests to assess the influence of graphene reinforcement on the composites' performance.FindingsThe findings reveal a marked enhancement in the composites impact resistance and energy absorption capabilities, which escalate with an increase in graphene content. Additionally, the study demonstrates a significant improvement in wear resistance, attributed to the superior mechanical properties, robust interface adhesion and effective dispersion of graphene. The use of surfactants for graphene treatment is identified as a crucial factor in these advancements, offering profound insights into the development of advanced composite materials for diverse industrial uses.Originality/valueThis study introduces a unique dispersion technique for graphene in epoxy composites, setting it apart from conventional methods. By focusing on the critical role of surfactant treatment in enhancing the mechanical properties of graphene-reinforced composites, it provides a novel insight into the optimization of impact and wear resistance.

Experimental and Numerical Investigation on the Motion Responses of a Spar-Type Floating Structure with Aquaculture Feeding Systems

The combination of aquaculture industry with floating offshore wind turbines has the potential to generate significant economic advantages for both industries. To investigate this potential, the present study focuses on analyzing the heave, and pitch dynamic responses of a Spar-type floating offshore wind turbine that incorporates an aquaculture feeding system. A series of water tank model tests, together with numerical calculations, were conducted using a 1/56 scale model of a 2 MW, displacement 3500 tons, floating Spar-type wind turbine. The feeding system was placed inside the Spar and slightly above the waterline by adjusting the configuration of the total weight. The weight of the feeding system in the experiments is 100 tons, capable of sustaining 300 tons of fish for an entire week, and the realistic applications have been expanded using the numerical calculation. For this reason, the present study serves a good case study for general understanding, because the integration of the feeding system inevitably raises the center of gravity of the structure and potentially affects its overall stability. The experiments revealed no discernible increase in the heave motion. Moreover, the pitch motion theoretically increased, but occasionally decreased in the experiments with the overall inclination angles being less than 1.2 degrees during the experiments. As a result, the present study supports the practice of integrating a Spar-type wind turbine with feeding systems. Future research should continue to comprehensively examine, both experimentally and numerically, the motion responses of the wind turbine and aquaculture facilities with varying configurations.

Continuum soil‐structure‐interaction model of the LHPOST6 shaking table reaction mass at UC San Diego

AbstractThe recently upgraded six Degree‐of‐Freedom Shaking Table, LHPOST6, at UC San Diego, underwent a series of forced vibration tests to evaluate the post‐upgrade dynamic response of the foundation‐soil system. The resulting data were instrumental in obtaining frequency response curves of the system, which were used to determine its low‐strain natural frequencies, effective viscous damping ratios, and reaction mass displacements. The extensive experimental data motivated the creation of a detailed Soil‐Structure‐Interaction model of the reaction mass‐soil system. The structure and soil were modeled using 3D Finite Elements in STKO‐OpenSees and calibrated with the acquired data via a parametric study. The 3D continuum FE model and the calibration procedure based on a single soil parameter (shear wave velocity profile) proved to be an effective tool to reproduce the experimental results accurately. This paper describes the Finite Element model, its calibration, and validation. In addition, the paper provides suggestions to simplify continuum models and promote their use in professional practice. The objectives of this campaign, alongside the growing accessibility of high‐performance computing, may serve as a step toward using SSI continuum models in the industry.

Auto-luminescence in seedlings: possible indicators for the gravimetric tide?

Germinating seedlings emit light in the visible range spontaneously, and these emissions are related to metabolism and reactive-oxygen species (ROS) processes. Several series of germination tests had such biological auto-luminescence (BAL) recorded in controlled conditions, fostering applications for the non-invasive, real-time evaluation of a seedling’s germinability and vigor when submitted to chemical and/or physical perturbations. However, long-term analysis of the BAL time-series of control samples conducted in different locations around the globe reveals that their BAL signals (and thus their metabolism) appear to follow the local gravimetric tide (g-tide) time profile. This indicates that the small daily and monthly variations in gravity acceleration due to the relative positioning of the Sun and Moon with respect to the Earth’s surface influence these signals. The gravimetric tide is a natural phenomenon that affects all things, fluid or solid, and is an uncontrollable variable in normal laboratory settings on Earth’s crust. All things on Earth have evolved under these pervasive cycles, with periods ranging from ∼12.2 h up to 28 d, which correspond to the Moon cycle. Tide-like cycles occur in living beings of different types, from the simplest bacteria to the most complex human beings, and we speculate that water availability at the molecular level could be a significant physical factor in modulating bio-activity by enabling protein folding and all metabolic pathways that require a synchronized organization to adapt to external environmental conditions. In this study, we summarize published results of a seedling’s BAL with cycle patterns resembling the g-tide in Limeira/BR, Prague/CZ, Leiden/NL, and Hamamatsu/JP and discuss the possible implications of this phenomenon for chronobiological studies.

Study on precursory recognition and integrated warning modeling to fracture in flawed sandstone under uniaxial compression

AbstractTo explore the precursory information and instability fracture of rocks, we conducted a series of uniaxial compression tests on flawed sandstone. An integrated warning modeling is developed to predict the fracture in flawed sandstone. The results show that both the peak strength and elastic modulus of flawed sandstone demonstrate an “inverted” Gaussian distribution relative to the ligament angle, reaching the minimum values at 60°. The elastic strain energy proportion shows a sharp drop‐off, whereas the proportion of dissipative energy increases in steps. The coalescence modes of flawed sandstone change from a mixed tensile‐shear failure approximately aligned with the axis to an oblique shear failure. An integrated warning model is developed by integrating a Multi‐Output Classifier (MOC) and Grid optimization (GO). The integrated warning model has an accuracy of 97.95%. Additionally, the sensitivity of the model is recorded at 99.26%, confirming its effectiveness in predicting the likelihood of fracturing.

Impact and mechanism analysis of industrial robot imports on export performance of Chinese firms

Digital import trade is of great practical significance for enhancing the export performance of enterprises and preventing external shocks. This paper empirically examines the impact and mechanism of industrial robot imports on Chinese firms’ export performance based on Chinese microenterprise data from 2004 to 2014. The study shows that the application of imported robots can significantly improve firms’ export performance, and this conclusion still holds after a series of robustness tests. Heterogeneity analysis shows that imported robots have a more significant role in boosting the export performance of state-owned enterprises and enterprises in capital- and technology-intensive industries; at the same time, they have a significant effect on the export performance of enterprises in different modes of trade; and they have a significant role in boosting the export performance of enterprises in eastern China compared with those in central and western regions. Mechanism analysis shows that the enhancement of export performance of enterprises by imported robots is mainly realized by promoting enterprise productivity and human capital efficiency. The policy implication of this paper is that in the era of digital trade, Chinese enterprises should fully utilize the import of digital products to enhance their productivity and promote the high-quality development of foreign trade.

A Fractional-Order Creep-Damage Model for Carbonaceous Shale Describing Coupled Damage Caused by Rainfall and Blasting

In order to better understand the shear creep behavior of weak interlayers (carbonaceous shale) under the coupling effect of the rainfall dry–wet cycle and blasting vibration, as well as quantitatively characterize the coupled damage of the rainfall dry–wet cycle and blasting vibration, a series of shear creep tests were carried out. The results show that the combined damage of the rainfall dry–wet cycle and blasting vibration greatly intensifies the creep effect of carbonaceous shale, leading to an increase in deceleration creep time, an increase in steady-state creep rate, and a decrease in long-term strength. The coupling damage of the rainfall dry–wet cycle and blasting vibration in carbonaceous shale was quantitatively characterized. Based on the fractional-order theory, a fractional-order creep-damage constitutive model (DNFVP) was established by introducing the Abel dashpot to describe the coupled damage of the rainfall wet–dry cycle and blasting vibration and the nonlinear creep acceleration characteristics. The three-dimensional creep equation of the model was derived. The effectiveness of the DNFVP model was verified through the inversion of model parameters and fitting of experimental data, providing a basis for in-depth research on the long-term stability of high slopes in mines with weak interlayers.

Joint Quality Assessment of Ultrasonic Metal Welded Parts by Fracture Surface Evaluation

In ultrasonic metal welding, low specific resistances and large joining surface cross-sections require the use of mechanical testing to quantify the joint quality. In this study, different quality features of ultrasonically welded joints made of pure copper sheet are investigated during the successive phases of joint formation. Two test series with different workpiece geometries are examined. It is shown that mechanical quality features such as shear and peel forces behave differently over the formation of the joint and are not transferable. As an alternative to these, laser scanning microscopy is used to record images of the fracture surface that describe the growth of the joint area during formation. The study finds that shear tensile force growth and joint area growth are non-linear and comparable, with optimized welds achieving joint areas of 30 mm2 out of 64 mm2 and 6 mm2 out of 16 mm2. Although overall quality increases with increasing welding time, the material strength in the joint zone decreases. Depending on the original rolling condition, between 43% and 59% of the original material strength can be identified as the joint strength. The automatic analysis of fracture images is a suitable alternative to mechanical testing for similar joints.

The Impact of Cashew Nut (Anacardium occidentale) Testa Tannin Feeding Ratio on the Chemical and Mechanical Characteristics of Leather Tanned from Cowhide, Goatskin and Sheepskin

In recent years, there has been a growing interest in exploring natural alternatives to synthetic tannins, driven by concerns over sustainability and environmental impact. Natural tannins offer several advantages, including biodegradability, renewability, and lower environmental impact compared to synthetic chemicals. Among the natural tannins under investigation, cashew nut testa tannin has emerged as a promising candidate due to its abundance, renewability, and potential benefits in leather tanning applications. This research investigated the impact of varying feeding ratios of cashew nut testa tannin on the chemical and mechanical characteristics of leather tanned from cowhide, goatskin, and sheepskin. The objective was to determine how different concentrations of cashew nut testa tannin influence the quality and performance of the leather. Leather samples were prepared using different feeding ratios of cashew nut testa tannin and subjected to a series of chemical and mechanical tests. The results indicated that the absorption of tannin and the resultant chemical stability varied with the type of hide or skin, with each exhibiting unique optimal ratios for tannin uptake. Higher tannin ratios generally improved the tensile and tear strength of the leather across all types, with significant enhancements noted in goatskin and sheepskin. However, an increase in tannin ratio reduced the flexibility of cowhide, while goatskin and sheepskin maintained adequate flexibility. The study demonstrates that cashew nut testa tannin is an effective and sustainable tanning agent, capable of producing quality leather. The findings suggest that the leather industry can utilize cashew nut testa tannin to enhance leather properties, with potential customization of tannin feeding ratios to meet specific performance requirements. Further research is recommended to explore long-term durability and economic viability on a commercial scale. This study contributes to the development of eco-friendly tanning practices and provides insights into optimizing the use of cashew nut testa tannin for various types of leather.

Machine learning-enabled detection of attention-deficit/hyperactivity disorder with multimodal physiological data: a case-control study

BackgroundAttention-Deficit/Hyperactivity Disorder (ADHD) is a multifaceted neurodevelopmental psychiatric condition that typically emerges during childhood but often persists into adulthood, significantly impacting individuals’ functioning, relationships, productivity, and overall quality of life. However, the current diagnostic process exhibits limitations that can significantly affect its overall effectiveness. Notably, its face-to-face and time-consuming nature, coupled with the reliance on subjective recall of historical information and clinician subjectivity, stand out as key challenges. To address these limitations, objective measures such as neuropsychological evaluations, imaging techniques and physiological monitoring of the Autonomic Nervous System functioning, have been explored.MethodsThe main aim of this study was to investigate whether physiological data (i.e., Electrodermal Activity, Heart Rate Variability, and Skin Temperature) can serve as meaningful indicators of ADHD, evaluating its utility in distinguishing adult ADHD patients. This observational, case-control study included a total of 76 adult participants (32 ADHD patients and 44 healthy controls) who underwent a series of Stroop tests, while their physiological data was passively collected using a multi-sensor wearable device. Univariate feature analysis was employed to identify the tests that triggered significant signal responses, while the Informative k-Nearest Neighbors (KNN) algorithm was used to filter out less informative data points. Finally, a machine-learning decision pipeline incorporating various classification algorithms, including Logistic Regression, KNN, Random Forests, and Support Vector Machines (SVM), was utilized for ADHD patient detection.ResultsResults indicate that the SVM-based model yielded the optimal performance, achieving 81.6% accuracy, maintaining a balance between the experimental and control groups, with sensitivity and specificity of 81.4% and 81.9%, respectively. Additionally, integration of data from all physiological signals yielded the best results, suggesting that each modality captures unique aspects of ADHD.ConclusionsThis study underscores the potential of physiological signals as valuable diagnostic indicators of adult ADHD. For the first time, to the best of our knowledge, our findings demonstrate that multimodal physiological data collected via wearable devices can complement traditional diagnostic approaches. Further research is warranted to explore the clinical applications and long-term implications of utilizing physiological markers in ADHD diagnosis and management.

Impact of heat treatment on the flavor stability of Longjing green tea beverages: Metabolomic insights and sensory correlations

The flavor stability of tea beverages during storage has long been a concern. The study aimed to explore the flavor stability of Longjing green tea beverage using accelerated heat treatment trials, addressing the shortage of lengthy storage trials. Sensory evaluations revealed changes in bitterness, umami, overall harmonization, astringency, and ripeness as treatment duration increased. Accompanied by a decrease in L-values, ΔE and an increase in a and b-values. Seventeen non-volatile metabolites and three volatile metabolites were identified differential among samples by metabolomics, with subsequent correlation analysis indicating associations between sensory attributes and specific metabolites. Umami was linked to epigallocatechin 3,5-digallate and alpha-D-glucopyranose, astringency was correlated with ellagic acid and 1-ethyl-1H-pyrrole. Ripeness showed associations with ellagic acid, 6,7-dihydroxycoumarin, heptanal, and benzaldehyde, and overall harmonization was linked to 6,7-dihydroxycoumarin, β-myrcene, α-terpineol, and heptanal. A series of verification tests confirmed the feasibility of accelerated heat treatment trials to replace traditional storage trials. These results offer valuable insights into unraveling the complex relationship between sensory and chemical profiles of green tea beverages.

Does enterprise digital transformation inhibit executives’ excess perks?—Evidence from China

ABSTRACT This study uses data on Chinese non-financially listed companies to examine the relationship between enterprise digital transformation and excess perks. We discovered that excess perks may be greatly mitigated by enterprise digital transformation and that these conclusions remain robust following a series of endogeneity and robustness tests. The mechanism test finds that reducing information asymmetry within firms is a path for enterprise digital transformation to suppress excess perks. Further analysis reveals the negative relationship between digital transformation and excess perks is more significant in firms with duality and lower institutional investor shareholdings. This study provides a theoretical basis for promoting enterprise digital transformation and improving corporate governance mechanisms.

Influence of Rock Block Content on Mechanical Properties of Coarse-Grained Fillers Stabilized with Fiber and Geopolymer

This study employed fiber and geopolymer to enhance the engineering performance of coarse-grained fillers. By conducting a series of comparative mechanical tests, the ideal mass mixing ratio design of geopolymer and fiber was investigated first. Then, the influence of rock block content on the mechanical properties of coarse-grained fillers stabilized with fiber and geopolymer was explored. The deformation damage characteristics of fiber- and geopolymer-stabilized coarse-grained fillers with different rock block contents were also discussed in the final test. The results show that the ideal mass mixing ratio of geopolymer for coarse-grained filler stabilization was 15% of dry fine-grained soil in weight and the ideal dosage and length of fiber was 0.4% of dry fine-grained soil in weight and 1.2 × 10−2 m. The compressive strength of fiber- and geopolymer-stabilized coarse-grained fillers shows a tendency to increase first, then decrease, and then re-increase with the increase in rock block contents. The best compressive strength and resistance to deformation were achieved when the rock block content was 30%. The failure mode of fiber- and geopolymer-stabilized coarse-grained fillers translated from shearing slip to vertical splitting as the rock block content increased. This study can provide a reference and support for the engineering application of coarse-grained fillers stabilized with fiber and geopolymer.

Does the deleveraging policy exacerbate tunneling? Empirical evidence from China

ABSTRACT This study investigates the impact of the deleveraging policy on tunneling, using China’s A-share listed firms. The deleveraging policy exacerbates tunneling and the result is robust after a series of tests. Further investigations show that tunneling of listed companies by non-state-owned controlling shareholders is particularly significant and audit opinions fail to reflect and inhibit tunneling. A way for large shareholders’ tunneling under deleveraging is collusion with management.

Can accolades make stakeholders tolerant: Award-winning and corporate litigation risk

Based on a sample of Chinese listed companies from 2007 to 2022, this paper examines whether corporate accolades are associated with a lower incidence of litigation. By holding earnings and other determinants of litigation, we find that obtaining and disclosing awards can reduce information asymmetry and improve corporate reputation, thereby reducing the litigation risk of firms. Our results still hold after a series of robustness tests. Further analysis finds that the mitigation effect of awards is more pronounced in operation disputes and debt disputes.

Shaking table test on progressive collapse of the double-layer cylindrical reticulated shell with infilled wall

Double-layer cylindrical reticulated shell has made rapid development in recent decades in China, which is widely used in the large-scale public buildings such as gymnasiums, airplane terminal, Shopping mall, etc. Stability and progressive collapse mechanism have been attracting a lot of attention because the large span space structure is largely affected by the geometry nonlinear, which makes it sensitive to the local damages. The infilled wall has a greater impact on the stiffness of the lower supporting structure due to sparse column grid. However, the influence of infilled walls on the collapse mechanism of large-span spatial structures is very complex due to the coupling of upper and lower structures. Therefore, the effects of infilled walls on double-layer cylindrical reticulated shell was investigated by a series of progressive collapse tests with shaking table. In order to evaluate the seismic performance and the capacity of resisting progressive collapse, the structural dynamic characteristics and response laws were obtained under different ground motions and input principal directions. The results indicated that the existence of infilled wall made the coupling between the lower supporting structure and the upper roof structure more complicated. The infilled walls influenced the structural damage evolution and development, mitigated the damage from the earthquake and changed the progressive collapse pattern, which made the catenary collapse mechanism occur when the structure collapsed. Although the further quantitative study is still needed, this paper provides lots of useful test data and conclusions, which gives references to the infilled wall design and seismic performance evaluation for double-layer cylindrical reticulated shell.

Stochastic nature of incipient plasticity in a body-centered cubic medium-entropy alloy

The stochastic nature of the small-scale incipient plasticity (i.e., “pop-in” behavior manifested as a sudden displacement excursion in the load-displacement curves) in a single grain of the body-centered cubic NbTiZr medium-entropy alloy is explored through a series of nanoindentation tests with three spherical tips having different radii (1.8, 3.4, and 8.2 μm). The maximum shear stress underneath the indenter shows distinct distributions depending on the tip radius, wherein both a narrow high-stress regime and a broad low-stress regime are observed. By recourse to deconvolution of the data and detailed statistical analysis, the two regimes were found to be dominated by homogeneous and heterogeneous yielding mechanisms, respectively. Upon hydrogen charging, the tip radius dependence is sustained, but the fraction of heterogeneous yielding is enhanced, which is due to the hydrogen's effect in assisting defect formation. The suggested scenarios for how the mechanisms are affected by the stressed volume (or tip radius) and hydrogen-induced structural changes were confirmed by direct observations of the deformation behavior underneath the indenter with cross-sectional transmission electron microscopy made on post-pop-in samples.

Synthetical improvement of dynamic mechanical property and toughness for precast concrete element based on optimization design of composition and curing regime

The brittleness and toughening measures of steam-cured concrete are currently less researched aspects. This study focuses on exploring the improvement in the toughness of steam-cured concrete and evaluating its influence on dynamic mechanical properties through a series of macroscopic performance tests. These tests include four-point bending tests, three-point bending fracture tests, uniaxial compression tests, and drop hammer impact tests, all conducted from the perspective of optimizing composition materials and steam curing regimes. The experimental results indicate that, under a relatively short heating time and a prolonged constant temperature curing period, the pure cement steam-cured concrete (S1 group), compared to the S2 group which used 20 % FA and 10 % GGBS to replace cement while also increasing the aggregate content with a modified steam curing regime, exhibited higher strength and elastic modulus but also showed greater brittleness. For example, the damping ratio increased to 0.6–0.7, the flexural-to-compressive strength ratio exceeded 6, and the number of specimens damaged by drop hammer impact significantly decreased, and the notch specimen exhibits lower peak load and displacement during fracture, with generally lower fracture parameter values. The fracture energy of the S2 group is 100–130 N·m-1 higher than that of the S1 group, reaching approximately 670 N·m-1, and the ductility index increased by 0.3–0.4. This research can provide technical support for the high-quality preparation of precast components using steam-cured concrete and offer a theoretical basis for reducing the brittleness of steam-cured concrete.

Anticoccidial activity of a botanical natural product based on eucalyptus, apigenin and eugenol against Eimeria tenella in broiler chickens

BackgroundChicken coccidiosis is an intracellular parasitic disease that presents major challenges to the development of the commercial poultry industry. Perennial drug selective pressure has led to the multi-drug resistance of chicken coccidia, which makes the prevention and control of chicken coccidiosis extremely difficult. In recent years, natural plant products have attracted the attention of researchers due to their inherent advantages, such as the absence of veterinary drug residues. The development of these natural products provides a new direction for the prevention and treatment of chicken coccidiosis.MethodsThe anticoccidial effect of a natural plant product combination formulation (eucalyptus oil + apigenin + eugenol essential oil) was tested against Eimeria tenella in broilers. To search for the optimal concentration of the combination formulation, we screened 120 broilers in a chicken cage trial in which 100 broilers were infected with 5 × 104 sporulated Eimeria tenella oocysts; broilers receiving a decoquinate solution was set up as a chemical control. The optimal anticoccidial concentration was determined by calculating the anticoccidial index (ACI), and the suitable concentration was used as the recommended dose for a series of safety dose assessment tests, such as feed conversion ratio (FCR), hematological indices and serum biochemical indices, as well as liver and kidney sections, at onefold (low dose), threefold (medium dose) and sixfold (high dose) the recommended dose (RD).ResultsThe results showed that this combination formulation of three plant natural products had a better anticoccidial effect than formulations containing two plant natural products or a single one, with an ACI of 169.3. The dose gradient anticoccidial test revealed that the high-dose formulation group had a better anticoccidial effect (ACI = 169.2) than the medium- and low-dose groups. The safety evaluation test showed that concentrations of the formulation at one-, three- and sixfold the RD were non-toxic to Arbor Acres broilers, indicating the high safety of the combination formulation.ConclusionsThe combination formulation showed not only a moderate anticoccidial effect but also had a high safety profile for broilers. The results of this study indicate a new alternative for the prevention and control of coccidiosis in broilers.Graphical